/*
** $Id: ltm.c,v 2.14 2011/06/02 19:31:40 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/


#include <string.h>

#define ltm_c
#define LUA_CORE

#include "lua.h"

#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"


static const char udatatypename[] = "userdata";

LUAI_DDEF const char *const luaT_typenames_[LUA_TOTALTAGS] = {
	"no value",
	"nil", "boolean", udatatypename, "number",
	"string", "table", "function", udatatypename, "thread",
	"proto", "upval"  /* these last two cases are used for tests only */
};


void luaT_init (lua_State *L) {
	static const char *const luaT_eventname[] = {  /* ORDER TM */
		"__index", "__newindex",
		"__gc", "__mode", "__len", "__eq",
		"__add", "__sub", "__mul", "__div", "__mod",
		"__pow", "__unm", "__lt", "__le",
		"__concat", "__call"
	};
	int i;
	for (i=0; i<TM_N; i++) {
		G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
		luaS_fix(G(L)->tmname[i]);  /* never collect these names */
	}
}


/*
** function to be used with macro "fasttm": optimized for absence of
** tag methods
*/
const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
	const TValue *tm = luaH_getstr(events, ename);
	lua_assert(event <= TM_EQ);
	if (ttisnil(tm)) {  /* no tag method? */
		events->flags |= cast_byte(1u<<event);  /* cache this fact */
		return NULL;
	}
	else return tm;
}


const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
	Table *mt;
	switch (ttypenv(o)) {
	case LUA_TTABLE:
		mt = hvalue(o)->metatable;
		break;
	case LUA_TUSERDATA:
		mt = uvalue(o)->metatable;
		break;
	default:
		mt = G(L)->mt[ttypenv(o)];
	}
	return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}

